Degradation of acetaminophen by Fenton and electro-Fenton processes in aerator reactor
Introduction
Huge amounts of commercial pharmaceuticals are used worldwide for medical and agricultural purposes. A current environmental issue is the effects of pharmaceuticals and personal care products (PPCPs). Human use of PPCPs results in excretion of unchanged constituents of PPCP through urine and faeces or as metabolites via municipal sewage systems. The PPCPs have been detected in waste streams and effluents from hospitals, wastewater treatment plants and livestock [1], [2], [3] and are considered a major emerging contaminant [4].
The various treatment technologies for removing or degrading PPCPs include advanced oxidation processes (AOPs) [5], which were defined in a 1987 study by Glaze et al. [6]. These processes generate hydroxyl radicals (OH) [7], [8], [9], which are powerful non-selective oxidants. Therefore, they can oxidize and mineralize almost all organic compounds into CO2 and inorganic ions [10], [11], [12], [13], [14]. A common AOP is the Fenton process, which is initiated by hydroxyl radicals formation during a Fenton reaction (Eq. (1)) [15].
In an acidic medium, this serial complex reaction generates the radicals shown in the following equations:
In the Fenton process, the ferrous ion (Fe2+) dosage is added to catalyze hydroxy peroxide (H2O2), which generates ferric hydroxide sludges that require an additional separation process and disposal. Application of the electrochemical method in Fenton process, which is known as the electro-Fenton (EF) process, can be performed in three ways [16]. The first approach is to apply ferrous ions so that hydrogen peroxide and ferrous ion are concurrently generated at the cathode. The second approach is to apply hydrogen peroxide and use an iron anode as a ferrous ion source [16] or to electrogenerate ferrous ion by reducing ferric hydroxide sludge [17]. The third approach is to electrogenerate ferrous ion and hydrogen peroxide at a sacrificial anode and cathode, respectively [18]. The studies have shown that toxic and refractory organics including dyes in wastewater can be destroyed by the electro-Fenton application [19], [20].
In the pharmaceuticals and personal care industries, acetaminophen paracetamol (ACTP) is among the most used and abused drugs in the world today. Recent studies have attempted to use AOPs for acetaminophen treatment [21], [22], [23], [24], [25]. These works have shown that electro-Fenton process can regenerated Fe2+ at the cathode, which also minimizes sludge production. However, no studies have compared acetaminophen degradation between Fenton and electro-Fenton processes. This study therefore compared acetaminophen degradation, chemical oxygen demand (COD) and total organic carbon (TOC) between the Fenton and electro-Fenton processes under similar batch mode experimental conditions. The Box–Behnken statistical design was applied to determine the optimum conditions for acetaminophen degradation.
Section snippets
Materials and reactor
Acetaminophen (C8H9NO2, Merck), hydrogen peroxide (H2O2, 35%, Merck), and ferrous sulfate hepta-hydrated (FeSO4·7H2O, Merck) were reagent grade and used without further purification. Fig. 1 presents the Fenton and electro-Fenton which were contained in a Plexiglas reservoir with dimensions of 21.5 × 15 × 25 cm3 with a volume of 8 L. Both processes were performed at room temperature in bath mode. To improve agitation, the stirrer was replaced by an aerator at the bottom of the reactor. Sludge was
Effect of operating parameters on acetaminophen degradation
The initial pH was limited to a range of 2–4. Fig. 2 shows how initial pH affected ACTP removal efficiency. At pH 2, ACTP removal efficiency increased with time and reached 91% at 90 min (Fig. 2a). The same trend was observed at pH 3 and 4. The ACTP removal efficiencies rapidly increased in first 10 min and then began to decrease after 10 min. At pH 3 and 4, removal efficiency approximated 80% at 10 min. The decreased ACTP removal efficiency at low pH probably resulted from formation of Fe(OH)+,
Conclusion
An electro-Fenton reactor with an aerator and a sludge outlet was used to measure acetaminophen degradation and to compare its efficiencies in ACTP degradation, COD removal and TOC removal with those of the Fenton process.
The ACTP degradation efficiency apparently increased from 12% to 84% in the Fenton process at pH 2 and from 20% to 94% in the electro-Fenton process at pH 4. Box–Behnken design (BBD) results confirmed that the Fe2+ and H2O2 concentrations positively affected ACTP removal
Acknowledgment
The authors would like to thank the National Science Council of Taiwan, for financially supporting this research under Contract No. NSC 99-2221-E-041-012-MY3.
References (27)
- et al.
Pilot survey monitoring pharmaceuticals and related compounds in a sewage treatment plant located on the Mediterranean coast
Chemosphere
(2007) - et al.
Occurrence of antibiotics in wastewater treatment facilities in Wisconsin, USA
Sci. Total. Environ.
(2006) Emerging pollutants in water analysis
Trends Anal. Chem.
(2003)- et al.
Ozonation and advanced oxidation technologies to remove endocrine disrupting chemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) in water effluents
J. Hazard. Mater.
(2007) - et al.
Degradation of melatonin by UV, UV/H2O2, Fe2+/H2O2 and UV/Fe2+/H2O2 processes
Sep. Purif. Technol.
(2009) - et al.
Decolorization of Mordant red 73 azo dye in water using H2O2/UV and photo-Fenton treatment
J. Hazard. Mater.
(2010) - et al.
Comparison of catalytic decomposition of hydrogen peroxide and catalytic degradation of phenol by immobilized iron oxides
Appl. Catal. A: General
(2008) - et al.
The reactor design and comparison of Fenton, electro-Fenton and photoelectron-Fenton processes for mineralization of benzene sulfonic acid (BSA)
J. Hazard. Mater.
(2008) - et al.
Degradation and detoxification of formaline wastewater by advanced oxidation processes
J. Hazard. Mater.
(2006) - et al.
A review of classic Fenton’s peroxidation as an advanced oxidation technique
J. Hazard. Mater.
(2003)
Degradation of 4-nitrophenol in aqueous medium by electro-Fenton method
J. Hazard. Mater.
Treatment of high strength hexamine-containing wastewater by electro-Fenton method
Water Res.
Aniline degradation by electro-Fenton and peroxi-coagulation processes using a flow reactor for wastewater treatment
Chemosphere
Cited by (88)
Application of vacuum membrane distillation-Fenton oxidation process for deep purification of low-level radioactive organic wastewater
2024, Separation and Purification TechnologyRemoval of the Insecticide Imidacloprid from Water in Commercial Formulation using Electro-Fenton and Photo-Electro-Fenton: Optimization of COD Removal through Response Surface Methodology RSM-CCD
2024, Chemical Engineering and Processing - Process IntensificationFacilitating peroxymonosulfate activation for effective antibiotics degradation from drinking water by photoelectrocatalytic system using MoS<inf>2</inf> embedded carbon substrate
2023, Chemical Engineering JournalCitation Excerpt :Hence, developing efficient techniques for removing antibiotics is of paramount significance. Advanced oxidation processes (AOPs), including Fenton processes [19,20], ozonation [21], photocatalysis [22,23], and peroxymonosulfate (PMS) oxidation [24] are promising and powerful processes for water treatment. These processes are more effective at removing recalcitrant organic compounds and ultimately mineralizing them into CO2 and H2O.
Visible light assisted heterogeneous photo-Fenton-like degradation of Rhodamine B based on the Co-POM/N-TiO<inf>2</inf> composites: Catalyst properties, photogenerated carrier transfer and degradation mechanism
2022, Colloids and Surfaces A: Physicochemical and Engineering Aspects